The present invention particularly refers to a cutting tool assembly of the above-specified kind for use in rotary cutting operations, such as e.g. milling, where a rotary torque is transferred from a tool shank to a cutting head mounted thereon.
When rotary cutting tools of the above kind are designed to work at small cutting diameters, it is often desirable that their cutting head be mounted on a tool shank in a self-clamping manner, which is often obtained by forming the cutting head and the tool shank with locking sections such as disclosed, for example, in EP 0 118 806.
EP 0 118 806 discloses a replaceable cutting head and a tool shank coaxially coupled together and having locking sections in the form of a centrally disposed and axially extending dovetail-shaped protrusion in the cutting head and a correspondingly shaped recess in the tool shank, which protrusion and recess co-axially interact in a male-female fashion. The protrusion and the recess both have fixation wings which are circumferentially spaced apart so that, during assembling, the fixation wings of the protrusion are initially inserted between the fixation wings of the recess and, upon rotation of the cutting head relative to the tool holder, they reach their final position in which the fixation wings of the recess overlie the corresponding fixation wings of the protrusion. The cutting head and the tool shank are further provided with positioning sections located peripherally with respect to the locking sections and abutting each other upon the rotation of the cutting head relative to the tool shank, which results in the interlocking of the locking sections in their final position, whereby the self-clamping of the cutting head on the tool shank is provided.
In order to enable the above-described interaction between the fixation wings of the locking sections of the cutting head and the tool shank, contacting surfaces of these wings need to have at least small axial and radial gaps therebetween, which leads to the necessity of providing the cutting tool assembly with additional means for accurate mutual positioning of the locking sections. Such additional means may be, for example, in the form of a resilient slit formed in the tool shank, as described in WO96/11079.
It is the object of the present invention to provide a new cutting head and a new tool shank for use therewith which, inter alia, have advantages in the above respect.